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gencode.c
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/*#define CHASE_CHAIN*/
/*
* Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that: (1) source code distributions
* retain the above copyright notice and this paragraph in its entirety, (2)
* distributions including binary code include the above copyright notice and
* this paragraph in its entirety in the documentation or other materials
* provided with the distribution, and (3) all advertising materials mentioning
* features or use of this software display the following acknowledgement:
* ``This product includes software developed by the University of California,
* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
* the University nor the names of its contributors may be used to endorse
* or promote products derived from this software without specific prior
* written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <pcap-types.h>
#ifdef _WIN32
#include <ws2tcpip.h>
#else
#include <sys/socket.h>
#ifdef __NetBSD__
#include <sys/param.h>
#endif
#include <netinet/in.h>
#include <arpa/inet.h>
#endif /* _WIN32 */
#include <stdlib.h>
#include <string.h>
#include <memory.h>
#include <setjmp.h>
#include <stdarg.h>
#ifdef MSDOS
#include "pcap-dos.h"
#endif
#include "pcap-int.h"
#include "ethertype.h"
#include "nlpid.h"
#include "llc.h"
#include "gencode.h"
#include "ieee80211.h"
#include "atmuni31.h"
#include "sunatmpos.h"
#include "ppp.h"
#include "pcap/sll.h"
#include "pcap/ipnet.h"
#include "arcnet.h"
#include "grammar.h"
#include "scanner.h"
#if defined(linux) && defined(PF_PACKET) && defined(SO_ATTACH_FILTER)
#include <linux/types.h>
#include <linux/if_packet.h>
#include <linux/filter.h>
#endif
#ifdef HAVE_NET_PFVAR_H
#include <sys/socket.h>
#include <net/if.h>
#include <net/pfvar.h>
#include <net/if_pflog.h>
#endif
#ifndef offsetof
#define offsetof(s, e) ((size_t)&((s *)0)->e)
#endif
#ifdef INET6
#ifdef _WIN32
#if defined(__MINGW32__) && defined(DEFINE_ADDITIONAL_IPV6_STUFF)
/* IPv6 address */
struct in6_addr
{
union
{
uint8_t u6_addr8[16];
uint16_t u6_addr16[8];
uint32_t u6_addr32[4];
} in6_u;
#define s6_addr in6_u.u6_addr8
#define s6_addr16 in6_u.u6_addr16
#define s6_addr32 in6_u.u6_addr32
#define s6_addr64 in6_u.u6_addr64
};
typedef unsigned short sa_family_t;
#define __SOCKADDR_COMMON(sa_prefix) \
sa_family_t sa_prefix##family
/* Ditto, for IPv6. */
struct sockaddr_in6
{
__SOCKADDR_COMMON (sin6_);
uint16_t sin6_port; /* Transport layer port # */
uint32_t sin6_flowinfo; /* IPv6 flow information */
struct in6_addr sin6_addr; /* IPv6 address */
};
#ifndef EAI_ADDRFAMILY
struct addrinfo {
int ai_flags; /* AI_PASSIVE, AI_CANONNAME */
int ai_family; /* PF_xxx */
int ai_socktype; /* SOCK_xxx */
int ai_protocol; /* 0 or IPPROTO_xxx for IPv4 and IPv6 */
size_t ai_addrlen; /* length of ai_addr */
char *ai_canonname; /* canonical name for hostname */
struct sockaddr *ai_addr; /* binary address */
struct addrinfo *ai_next; /* next structure in linked list */
};
#endif /* EAI_ADDRFAMILY */
#endif /* defined(__MINGW32__) && defined(DEFINE_ADDITIONAL_IPV6_STUFF) */
#else /* _WIN32 */
#include <netdb.h> /* for "struct addrinfo" */
#endif /* _WIN32 */
#endif /* INET6 */
#include <pcap/namedb.h>
#include "nametoaddr.h"
#define ETHERMTU 1500
#ifndef ETHERTYPE_TEB
#define ETHERTYPE_TEB 0x6558
#endif
#ifndef IPPROTO_HOPOPTS
#define IPPROTO_HOPOPTS 0
#endif
#ifndef IPPROTO_ROUTING
#define IPPROTO_ROUTING 43
#endif
#ifndef IPPROTO_FRAGMENT
#define IPPROTO_FRAGMENT 44
#endif
#ifndef IPPROTO_DSTOPTS
#define IPPROTO_DSTOPTS 60
#endif
#ifndef IPPROTO_SCTP
#define IPPROTO_SCTP 132
#endif
#define GENEVE_PORT 6081
#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif
#define JMP(c) ((c)|BPF_JMP|BPF_K)
/*
* "Push" the current value of the link-layer header type and link-layer
* header offset onto a "stack", and set a new value. (It's not a
* full-blown stack; we keep only the top two items.)
*/
#define PUSH_LINKHDR(cs, new_linktype, new_is_variable, new_constant_part, new_reg) \
{ \
(cs)->prevlinktype = (cs)->linktype; \
(cs)->off_prevlinkhdr = (cs)->off_linkhdr; \
(cs)->linktype = (new_linktype); \
(cs)->off_linkhdr.is_variable = (new_is_variable); \
(cs)->off_linkhdr.constant_part = (new_constant_part); \
(cs)->off_linkhdr.reg = (new_reg); \
(cs)->is_geneve = 0; \
}
/*
* Offset "not set" value.
*/
#define OFFSET_NOT_SET 0xffffffffU
/*
* Absolute offsets, which are offsets from the beginning of the raw
* packet data, are, in the general case, the sum of a variable value
* and a constant value; the variable value may be absent, in which
* case the offset is only the constant value, and the constant value
* may be zero, in which case the offset is only the variable value.
*
* bpf_abs_offset is a structure containing all that information:
*
* is_variable is 1 if there's a variable part.
*
* constant_part is the constant part of the value, possibly zero;
*
* if is_variable is 1, reg is the register number for a register
* containing the variable value if the register has been assigned,
* and -1 otherwise.
*/
typedef struct {
int is_variable;
u_int constant_part;
int reg;
} bpf_abs_offset;
/*
* Value passed to gen_load_a() to indicate what the offset argument
* is relative to the beginning of.
*/
enum e_offrel {
OR_PACKET, /* full packet data */
OR_LINKHDR, /* link-layer header */
OR_PREVLINKHDR, /* previous link-layer header */
OR_LLC, /* 802.2 LLC header */
OR_PREVMPLSHDR, /* previous MPLS header */
OR_LINKTYPE, /* link-layer type */
OR_LINKPL, /* link-layer payload */
OR_LINKPL_NOSNAP, /* link-layer payload, with no SNAP header at the link layer */
OR_TRAN_IPV4, /* transport-layer header, with IPv4 network layer */
OR_TRAN_IPV6 /* transport-layer header, with IPv6 network layer */
};
/*
* We divy out chunks of memory rather than call malloc each time so
* we don't have to worry about leaking memory. It's probably
* not a big deal if all this memory was wasted but if this ever
* goes into a library that would probably not be a good idea.
*
* XXX - this *is* in a library....
*/
#define NCHUNKS 16
#define CHUNK0SIZE 1024
struct chunk {
size_t n_left;
void *m;
};
/* Code generator state */
struct _compiler_state {
jmp_buf top_ctx;
pcap_t *bpf_pcap;
struct icode ic;
int snaplen;
int linktype;
int prevlinktype;
int outermostlinktype;
bpf_u_int32 netmask;
int no_optimize;
/* Hack for handling VLAN and MPLS stacks. */
u_int label_stack_depth;
u_int vlan_stack_depth;
/* XXX */
u_int pcap_fddipad;
#ifdef INET6
/*
* As errors are handled by a longjmp, anything allocated must
* be freed in the longjmp handler, so it must be reachable
* from that handler.
*
* One thing that's allocated is the result of pcap_nametoaddrinfo();
* it must be freed with freeaddrinfo(). This variable points to
* any addrinfo structure that would need to be freed.
*/
struct addrinfo *ai;
#endif
/*
* Various code constructs need to know the layout of the packet.
* These values give the necessary offsets from the beginning
* of the packet data.
*/
/*
* Absolute offset of the beginning of the link-layer header.
*/
bpf_abs_offset off_linkhdr;
/*
* If we're checking a link-layer header for a packet encapsulated
* in another protocol layer, this is the equivalent information
* for the previous layers' link-layer header from the beginning
* of the raw packet data.
*/
bpf_abs_offset off_prevlinkhdr;
/*
* This is the equivalent information for the outermost layers'
* link-layer header.
*/
bpf_abs_offset off_outermostlinkhdr;
/*
* Absolute offset of the beginning of the link-layer payload.
*/
bpf_abs_offset off_linkpl;
/*
* "off_linktype" is the offset to information in the link-layer
* header giving the packet type. This is an absolute offset
* from the beginning of the packet.
*
* For Ethernet, it's the offset of the Ethernet type field; this
* means that it must have a value that skips VLAN tags.
*
* For link-layer types that always use 802.2 headers, it's the
* offset of the LLC header; this means that it must have a value
* that skips VLAN tags.
*
* For PPP, it's the offset of the PPP type field.
*
* For Cisco HDLC, it's the offset of the CHDLC type field.
*
* For BSD loopback, it's the offset of the AF_ value.
*
* For Linux cooked sockets, it's the offset of the type field.
*
* off_linktype.constant_part is set to OFFSET_NOT_SET for no
* encapsulation, in which case, IP is assumed.
*/
bpf_abs_offset off_linktype;
/*
* TRUE if the link layer includes an ATM pseudo-header.
*/
int is_atm;
/*
* TRUE if "geneve" appeared in the filter; it causes us to
* generate code that checks for a Geneve header and assume
* that later filters apply to the encapsulated payload.
*/
int is_geneve;
/*
* TRUE if we need variable length part of VLAN offset
*/
int is_vlan_vloffset;
/*
* These are offsets for the ATM pseudo-header.
*/
u_int off_vpi;
u_int off_vci;
u_int off_proto;
/*
* These are offsets for the MTP2 fields.
*/
u_int off_li;
u_int off_li_hsl;
/*
* These are offsets for the MTP3 fields.
*/
u_int off_sio;
u_int off_opc;
u_int off_dpc;
u_int off_sls;
/*
* This is the offset of the first byte after the ATM pseudo_header,
* or -1 if there is no ATM pseudo-header.
*/
u_int off_payload;
/*
* These are offsets to the beginning of the network-layer header.
* They are relative to the beginning of the link-layer payload
* (i.e., they don't include off_linkhdr.constant_part or
* off_linkpl.constant_part).
*
* If the link layer never uses 802.2 LLC:
*
* "off_nl" and "off_nl_nosnap" are the same.
*
* If the link layer always uses 802.2 LLC:
*
* "off_nl" is the offset if there's a SNAP header following
* the 802.2 header;
*
* "off_nl_nosnap" is the offset if there's no SNAP header.
*
* If the link layer is Ethernet:
*
* "off_nl" is the offset if the packet is an Ethernet II packet
* (we assume no 802.3+802.2+SNAP);
*
* "off_nl_nosnap" is the offset if the packet is an 802.3 packet
* with an 802.2 header following it.
*/
u_int off_nl;
u_int off_nl_nosnap;
/*
* Here we handle simple allocation of the scratch registers.
* If too many registers are alloc'd, the allocator punts.
*/
int regused[BPF_MEMWORDS];
int curreg;
/*
* Memory chunks.
*/
struct chunk chunks[NCHUNKS];
int cur_chunk;
};
void
bpf_syntax_error(compiler_state_t *cstate, const char *msg)
{
bpf_error(cstate, "syntax error in filter expression: %s", msg);
/* NOTREACHED */
}
/* VARARGS */
void
bpf_error(compiler_state_t *cstate, const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
if (cstate->bpf_pcap != NULL)
(void)pcap_vsnprintf(pcap_geterr(cstate->bpf_pcap),
PCAP_ERRBUF_SIZE, fmt, ap);
va_end(ap);
longjmp(cstate->top_ctx, 1);
/* NOTREACHED */
}
static void init_linktype(compiler_state_t *, pcap_t *);
static void init_regs(compiler_state_t *);
static int alloc_reg(compiler_state_t *);
static void free_reg(compiler_state_t *, int);
static void initchunks(compiler_state_t *cstate);
static void *newchunk(compiler_state_t *cstate, size_t);
static void freechunks(compiler_state_t *cstate);
static inline struct block *new_block(compiler_state_t *cstate, int);
static inline struct slist *new_stmt(compiler_state_t *cstate, int);
static struct block *gen_retblk(compiler_state_t *cstate, int);
static inline void syntax(compiler_state_t *cstate);
static void backpatch(struct block *, struct block *);
static void merge(struct block *, struct block *);
static struct block *gen_cmp(compiler_state_t *, enum e_offrel, u_int,
u_int, bpf_int32);
static struct block *gen_cmp_gt(compiler_state_t *, enum e_offrel, u_int,
u_int, bpf_int32);
static struct block *gen_cmp_ge(compiler_state_t *, enum e_offrel, u_int,
u_int, bpf_int32);
static struct block *gen_cmp_lt(compiler_state_t *, enum e_offrel, u_int,
u_int, bpf_int32);
static struct block *gen_cmp_le(compiler_state_t *, enum e_offrel, u_int,
u_int, bpf_int32);
static struct block *gen_mcmp(compiler_state_t *, enum e_offrel, u_int,
u_int, bpf_int32, bpf_u_int32);
static struct block *gen_bcmp(compiler_state_t *, enum e_offrel, u_int,
u_int, const u_char *);
static struct block *gen_ncmp(compiler_state_t *, enum e_offrel, bpf_u_int32,
bpf_u_int32, bpf_u_int32, bpf_u_int32, int, bpf_int32);
static struct slist *gen_load_absoffsetrel(compiler_state_t *, bpf_abs_offset *,
u_int, u_int);
static struct slist *gen_load_a(compiler_state_t *, enum e_offrel, u_int,
u_int);
static struct slist *gen_loadx_iphdrlen(compiler_state_t *);
static struct block *gen_uncond(compiler_state_t *, int);
static inline struct block *gen_true(compiler_state_t *);
static inline struct block *gen_false(compiler_state_t *);
static struct block *gen_ether_linktype(compiler_state_t *, int);
static struct block *gen_ipnet_linktype(compiler_state_t *, int);
static struct block *gen_linux_sll_linktype(compiler_state_t *, int);
static struct slist *gen_load_prism_llprefixlen(compiler_state_t *);
static struct slist *gen_load_avs_llprefixlen(compiler_state_t *);
static struct slist *gen_load_radiotap_llprefixlen(compiler_state_t *);
static struct slist *gen_load_ppi_llprefixlen(compiler_state_t *);
static void insert_compute_vloffsets(compiler_state_t *, struct block *);
static struct slist *gen_abs_offset_varpart(compiler_state_t *,
bpf_abs_offset *);
static int ethertype_to_ppptype(int);
static struct block *gen_linktype(compiler_state_t *, int);
static struct block *gen_snap(compiler_state_t *, bpf_u_int32, bpf_u_int32);
static struct block *gen_llc_linktype(compiler_state_t *, int);
static struct block *gen_hostop(compiler_state_t *, bpf_u_int32, bpf_u_int32,
int, int, u_int, u_int);
#ifdef INET6
static struct block *gen_hostop6(compiler_state_t *, struct in6_addr *,
struct in6_addr *, int, int, u_int, u_int);
#endif
static struct block *gen_ahostop(compiler_state_t *, const u_char *, int);
static struct block *gen_ehostop(compiler_state_t *, const u_char *, int);
static struct block *gen_fhostop(compiler_state_t *, const u_char *, int);
static struct block *gen_thostop(compiler_state_t *, const u_char *, int);
static struct block *gen_wlanhostop(compiler_state_t *, const u_char *, int);
static struct block *gen_ipfchostop(compiler_state_t *, const u_char *, int);
static struct block *gen_dnhostop(compiler_state_t *, bpf_u_int32, int);
static struct block *gen_mpls_linktype(compiler_state_t *, int);
static struct block *gen_host(compiler_state_t *, bpf_u_int32, bpf_u_int32,
int, int, int);
#ifdef INET6
static struct block *gen_host6(compiler_state_t *, struct in6_addr *,
struct in6_addr *, int, int, int);
#endif
#ifndef INET6
static struct block *gen_gateway(compiler_state_t *, const u_char *,
bpf_u_int32 **, int, int);
#endif
static struct block *gen_ipfrag(compiler_state_t *);
static struct block *gen_portatom(compiler_state_t *, int, bpf_int32);
static struct block *gen_portrangeatom(compiler_state_t *, int, bpf_int32,
bpf_int32);
static struct block *gen_portatom6(compiler_state_t *, int, bpf_int32);
static struct block *gen_portrangeatom6(compiler_state_t *, int, bpf_int32,
bpf_int32);
struct block *gen_portop(compiler_state_t *, int, int, int);
static struct block *gen_port(compiler_state_t *, int, int, int);
struct block *gen_portrangeop(compiler_state_t *, int, int, int, int);
static struct block *gen_portrange(compiler_state_t *, int, int, int, int);
struct block *gen_portop6(compiler_state_t *, int, int, int);
static struct block *gen_port6(compiler_state_t *, int, int, int);
struct block *gen_portrangeop6(compiler_state_t *, int, int, int, int);
static struct block *gen_portrange6(compiler_state_t *, int, int, int, int);
static int lookup_proto(compiler_state_t *, const char *, int);
static struct block *gen_protochain(compiler_state_t *, int, int, int);
static struct block *gen_proto(compiler_state_t *, int, int, int);
static struct slist *xfer_to_x(compiler_state_t *, struct arth *);
static struct slist *xfer_to_a(compiler_state_t *, struct arth *);
static struct block *gen_mac_multicast(compiler_state_t *, int);
static struct block *gen_len(compiler_state_t *, int, int);
static struct block *gen_check_802_11_data_frame(compiler_state_t *);
static struct block *gen_geneve_ll_check(compiler_state_t *cstate);
static struct block *gen_ppi_dlt_check(compiler_state_t *);
static struct block *gen_msg_abbrev(compiler_state_t *, int type);
static void
initchunks(compiler_state_t *cstate)
{
int i;
for (i = 0; i < NCHUNKS; i++) {
cstate->chunks[i].n_left = 0;
cstate->chunks[i].m = NULL;
}
cstate->cur_chunk = 0;
}
static void *
newchunk(compiler_state_t *cstate, size_t n)
{
struct chunk *cp;
int k;
size_t size;
#ifndef __NetBSD__
/* XXX Round up to nearest long. */
n = (n + sizeof(long) - 1) & ~(sizeof(long) - 1);
#else
/* XXX Round up to structure boundary. */
n = ALIGN(n);
#endif
cp = &cstate->chunks[cstate->cur_chunk];
if (n > cp->n_left) {
++cp, k = ++cstate->cur_chunk;
if (k >= NCHUNKS)
bpf_error(cstate, "out of memory");
size = CHUNK0SIZE << k;
cp->m = (void *)malloc(size);
if (cp->m == NULL)
bpf_error(cstate, "out of memory");
memset((char *)cp->m, 0, size);
cp->n_left = size;
if (n > size)
bpf_error(cstate, "out of memory");
}
cp->n_left -= n;
return (void *)((char *)cp->m + cp->n_left);
}
static void
freechunks(compiler_state_t *cstate)
{
int i;
for (i = 0; i < NCHUNKS; ++i)
if (cstate->chunks[i].m != NULL)
free(cstate->chunks[i].m);
}
/*
* A strdup whose allocations are freed after code generation is over.
*/
char *
sdup(compiler_state_t *cstate, const char *s)
{
size_t n = strlen(s) + 1;
char *cp = newchunk(cstate, n);
strlcpy(cp, s, n);
return (cp);
}
static inline struct block *
new_block(compiler_state_t *cstate, int code)
{
struct block *p;
p = (struct block *)newchunk(cstate, sizeof(*p));
p->s.code = code;
p->head = p;
return p;
}
static inline struct slist *
new_stmt(compiler_state_t *cstate, int code)
{
struct slist *p;
p = (struct slist *)newchunk(cstate, sizeof(*p));
p->s.code = code;
return p;
}
static struct block *
gen_retblk(compiler_state_t *cstate, int v)
{
struct block *b = new_block(cstate, BPF_RET|BPF_K);
b->s.k = v;
return b;
}
static inline void
syntax(compiler_state_t *cstate)
{
bpf_error(cstate, "syntax error in filter expression");
}
int
pcap_compile(pcap_t *p, struct bpf_program *program,
const char *buf, int optimize, bpf_u_int32 mask)
{
#ifdef _WIN32
static int done = 0;
#endif
compiler_state_t cstate;
const char * volatile xbuf = buf;
yyscan_t scanner = NULL;
YY_BUFFER_STATE in_buffer = NULL;
u_int len;
int rc;
/*
* If this pcap_t hasn't been activated, it doesn't have a
* link-layer type, so we can't use it.
*/
if (!p->activated) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"not-yet-activated pcap_t passed to pcap_compile");
return (-1);
}
#ifdef _WIN32
if (!done)
pcap_wsockinit();
done = 1;
#endif
#ifdef ENABLE_REMOTE
/*
* If the device on which we're capturing need to be notified
* that a new filter is being compiled, do so.
*
* This allows them to save a copy of it, in case, for example,
* they're implementing a form of remote packet capture, and
* want the remote machine to filter out the packets in which
* it's sending the packets it's captured.
*
* XXX - the fact that we happen to be compiling a filter
* doesn't necessarily mean we'll be installing it as the
* filter for this pcap_t; we might be running it from userland
* on captured packets to do packet classification. We really
* need a better way of handling this, but this is all that
* the WinPcap code did.
*/
if (p->save_current_filter_op != NULL)
(p->save_current_filter_op)(p, buf);
#endif
initchunks(&cstate);
cstate.no_optimize = 0;
#ifdef INET6
cstate.ai = NULL;
#endif
cstate.ic.root = NULL;
cstate.ic.cur_mark = 0;
cstate.bpf_pcap = p;
init_regs(&cstate);
if (setjmp(cstate.top_ctx)) {
#ifdef INET6
if (cstate.ai != NULL)
freeaddrinfo(cstate.ai);
#endif
rc = -1;
goto quit;
}
cstate.netmask = mask;
cstate.snaplen = pcap_snapshot(p);
if (cstate.snaplen == 0) {
pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"snaplen of 0 rejects all packets");
rc = -1;
goto quit;
}
if (pcap_lex_init(&scanner) != 0)
bpf_error(&cstate, "can't initialize scanner: %s", pcap_strerror(errno));
in_buffer = pcap__scan_string(xbuf ? xbuf : "", scanner);
/*
* Associate the compiler state with the lexical analyzer
* state.
*/
pcap_set_extra(&cstate, scanner);
init_linktype(&cstate, p);
(void)pcap_parse(scanner, &cstate);
if (cstate.ic.root == NULL)
cstate.ic.root = gen_retblk(&cstate, cstate.snaplen);
if (optimize && !cstate.no_optimize) {
bpf_optimize(&cstate, &cstate.ic);
if (cstate.ic.root == NULL ||
(cstate.ic.root->s.code == (BPF_RET|BPF_K) && cstate.ic.root->s.k == 0))
bpf_error(&cstate, "expression rejects all packets");
}
program->bf_insns = icode_to_fcode(&cstate, &cstate.ic, cstate.ic.root, &len);
program->bf_len = len;
rc = 0; /* We're all okay */
quit:
/*
* Clean up everything for the lexical analyzer.
*/
if (in_buffer != NULL)
pcap__delete_buffer(in_buffer, scanner);
if (scanner != NULL)
pcap_lex_destroy(scanner);
/*
* Clean up our own allocated memory.
*/
freechunks(&cstate);
return (rc);
}
/*
* entry point for using the compiler with no pcap open
* pass in all the stuff that is needed explicitly instead.
*/
int
pcap_compile_nopcap(int snaplen_arg, int linktype_arg,
struct bpf_program *program,
const char *buf, int optimize, bpf_u_int32 mask)
{
pcap_t *p;
int ret;
p = pcap_open_dead(linktype_arg, snaplen_arg);
if (p == NULL)
return (-1);
ret = pcap_compile(p, program, buf, optimize, mask);
pcap_close(p);
return (ret);
}
/*
* Clean up a "struct bpf_program" by freeing all the memory allocated
* in it.
*/
void
pcap_freecode(struct bpf_program *program)
{
program->bf_len = 0;
if (program->bf_insns != NULL) {
free((char *)program->bf_insns);
program->bf_insns = NULL;
}
}
/*
* Backpatch the blocks in 'list' to 'target'. The 'sense' field indicates
* which of the jt and jf fields has been resolved and which is a pointer
* back to another unresolved block (or nil). At least one of the fields
* in each block is already resolved.
*/
static void
backpatch(list, target)
struct block *list, *target;
{
struct block *next;
while (list) {
if (!list->sense) {
next = JT(list);
JT(list) = target;
} else {
next = JF(list);
JF(list) = target;
}
list = next;
}
}
/*
* Merge the lists in b0 and b1, using the 'sense' field to indicate
* which of jt and jf is the link.
*/
static void
merge(b0, b1)
struct block *b0, *b1;
{
register struct block **p = &b0;
/* Find end of list. */
while (*p)
p = !((*p)->sense) ? &JT(*p) : &JF(*p);
/* Concatenate the lists. */
*p = b1;
}
void
finish_parse(compiler_state_t *cstate, struct block *p)
{
struct block *ppi_dlt_check;
/*
* Insert before the statements of the first (root) block any
* statements needed to load the lengths of any variable-length
* headers into registers.
*
* XXX - a fancier strategy would be to insert those before the
* statements of all blocks that use those lengths and that
* have no predecessors that use them, so that we only compute
* the lengths if we need them. There might be even better
* approaches than that.
*
* However, those strategies would be more complicated, and
* as we don't generate code to compute a length if the
* program has no tests that use the length, and as most
* tests will probably use those lengths, we would just
* postpone computing the lengths so that it's not done
* for tests that fail early, and it's not clear that's
* worth the effort.
*/
insert_compute_vloffsets(cstate, p->head);
/*
* For DLT_PPI captures, generate a check of the per-packet
* DLT value to make sure it's DLT_IEEE802_11.
*
* XXX - TurboCap cards use DLT_PPI for Ethernet.
* Can we just define some DLT_ETHERNET_WITH_PHDR pseudo-header
* with appropriate Ethernet information and use that rather
* than using something such as DLT_PPI where you don't know
* the link-layer header type until runtime, which, in the
* general case, would force us to generate both Ethernet *and*
* 802.11 code (*and* anything else for which PPI is used)
* and choose between them early in the BPF program?
*/
ppi_dlt_check = gen_ppi_dlt_check(cstate);
if (ppi_dlt_check != NULL)
gen_and(ppi_dlt_check, p);
backpatch(p, gen_retblk(cstate, cstate->snaplen));
p->sense = !p->sense;
backpatch(p, gen_retblk(cstate, 0));
cstate->ic.root = p->head;
}
void
gen_and(b0, b1)
struct block *b0, *b1;
{
backpatch(b0, b1->head);
b0->sense = !b0->sense;
b1->sense = !b1->sense;
merge(b1, b0);
b1->sense = !b1->sense;
b1->head = b0->head;
}
void
gen_or(b0, b1)
struct block *b0, *b1;
{
b0->sense = !b0->sense;
backpatch(b0, b1->head);
b0->sense = !b0->sense;
merge(b1, b0);
b1->head = b0->head;
}
void
gen_not(b)
struct block *b;
{
b->sense = !b->sense;
}
static struct block *
gen_cmp(compiler_state_t *cstate, enum e_offrel offrel, u_int offset,
u_int size, bpf_int32 v)
{
return gen_ncmp(cstate, offrel, offset, size, 0xffffffff, BPF_JEQ, 0, v);
}
static struct block *
gen_cmp_gt(compiler_state_t *cstate, enum e_offrel offrel, u_int offset,
u_int size, bpf_int32 v)
{
return gen_ncmp(cstate, offrel, offset, size, 0xffffffff, BPF_JGT, 0, v);
}
static struct block *
gen_cmp_ge(compiler_state_t *cstate, enum e_offrel offrel, u_int offset,
u_int size, bpf_int32 v)
{
return gen_ncmp(cstate, offrel, offset, size, 0xffffffff, BPF_JGE, 0, v);
}
static struct block *
gen_cmp_lt(compiler_state_t *cstate, enum e_offrel offrel, u_int offset,
u_int size, bpf_int32 v)
{
return gen_ncmp(cstate, offrel, offset, size, 0xffffffff, BPF_JGE, 1, v);
}
static struct block *
gen_cmp_le(compiler_state_t *cstate, enum e_offrel offrel, u_int offset,
u_int size, bpf_int32 v)
{
return gen_ncmp(cstate, offrel, offset, size, 0xffffffff, BPF_JGT, 1, v);
}
static struct block *
gen_mcmp(compiler_state_t *cstate, enum e_offrel offrel, u_int offset,
u_int size, bpf_int32 v, bpf_u_int32 mask)
{
return gen_ncmp(cstate, offrel, offset, size, mask, BPF_JEQ, 0, v);
}
static struct block *
gen_bcmp(compiler_state_t *cstate, enum e_offrel offrel, u_int offset,
u_int size, const u_char *v)
{
register struct block *b, *tmp;
b = NULL;
while (size >= 4) {
register const u_char *p = &v[size - 4];
bpf_int32 w = ((bpf_int32)p[0] << 24) |
((bpf_int32)p[1] << 16) | ((bpf_int32)p[2] << 8) | p[3];
tmp = gen_cmp(cstate, offrel, offset + size - 4, BPF_W, w);
if (b != NULL)
gen_and(b, tmp);
b = tmp;
size -= 4;
}
while (size >= 2) {
register const u_char *p = &v[size - 2];
bpf_int32 w = ((bpf_int32)p[0] << 8) | p[1];
tmp = gen_cmp(cstate, offrel, offset + size - 2, BPF_H, w);
if (b != NULL)